Automatic controlling apparatus for pumps, compressors, and the like



June 26, 1928. 1,674,984

K. MULLER AUTOMATIC CONTROLLING APPARATUS FOR PUMPS, COMPRESiSORS, AND THE LIKE Filed March 29, 1926 s Sheets-Sheet 1 Jm'en for 2 Karl Millie/- June 26, 1928. 1,674,984

K. MULLER AUTOMATIC CONTROLLING APPARATUS FOR PUMPS, COMPRESSORS, AND THE LIKE Filed March 29, 1926 3 Shoots-Sheet 9 J12 V811 for 2 June 26, 1928.

l 1,674,984- K. MULLER AUTOMATIC CONTROLLING APPARATUS FOR PUMPS, COMPRESSORS, AND THE LIKE Filed March 29, 1926 3 Sheets-Shea Jm pnlorg Karl Ma Patented June 26, 1928.

UNITED STATES PATENT OFFICE.

, KARL MfILLER, 0F ESSEN-ON-THE-RUHR, GERMANY.

Application filed March 29, 1926, Serial N01 98.307. and in Germany March 30, 1925.

The subject matter of the present invention is an automatic controlling apparatus for pumps, compressors and thehke which is particularly intended to start up the pump or the compressor when the pressure in the conduit or in a receiver supplied by the pum or'the compressor falls below a predeterminedvalue and'on the other hand to bring the pump or the compressor to a standstill again when'a maximum pressure has been reached. The starting apparatus comprises a starting switch, of a type known per se, which is moved in the direction for starting the driving motor of the pump or the compressor by means of a weight and in the opposite direction, by the pressure medium through theagency of a piston which is fitted in a sd-calledfegulating cylinder. The apparatus comprises further a device, whieh'is also known per se, for unloading the pump or compressor. In the controlling apparatus in accordance with the invention the pressure medium cylinder for moving the starting switch and the device for unloading the pump are controlled by means of'a valve which in one end position, namely, its position of rest. subjects at least the regulating cylinder for the starting switch and in some cases also a fluid pressure actuating unloading valve to pressure. In its middle position on the other hand the valve relieves the regulating cylinder from pressure and subjects the unloading valve to pressure and. finally, in its other end position, namely in its operating position, it relieves not only the regulating cylinder for the starting switch but also the unloading valve from pressure. The adjustment of this valve is effected in accordance with the invention partly by an electro-magnet which is connected in shunt with the circuit of the motor and is itself cont rolled by means of a switch actuated by the pressure medium, and partly by the actuating weight of the starting switch, in such a manner that the movement of the valve from its position of restto its middle position is effected by the armatureof the electro-magnet being attracted, and the movement from the middle position to the operating position, after the starting procedure has been completed. is on the contrary efi'ected by the actuating weight of the starting switch, while the return movement of the valve into its position of rest is effected by the fall of the armature- Finally, even if mechanical disturbances occur within the starting switch, starting up of the motor under load is avoided with certainty, since the unloading of the pump or the compressor can not take place until the starter-has made connection with the last contact of the series of contacts over which it travels, that is when the starting'up of the motor is completed.

- The new controlling apparatus is distinguishable from the known apparatus serving the same purpose by its exact and reliable operation in addition to its greater simplicity. It possesses the further .adv'antage that the driving motor for the pump or the like is always switched over so as to run at full speed 'when the compressor is unloaded not only when everything is in order but also ifany electrical disturbances occur so that the re-starting of the driving motor only when the pump or the compressor is'unloaded is ensured. If, for instance. owing to failure of the voltage or in consequence of automatic disconnection by an overload relay. current ceases to flow in the electromagnet the falling armature of the electromagnet returns the controlling valve into its original position, the consequence of which is that the starting switch is also returned into its original position by the pressure medium admitted to its regulating cylinder. Furthermore, there is an avoidance, when the voltage is again applied, of the starting switch being sctin the position for full speed and the pump or compressor being subjected to full load, so that damage to the installation is prevented.

The new apparatus can also be so con-- structed that, when a predetermined pressure is reached in the receiver supplied by the. pump or the compressor.- instead of both of these latter-named agents being brought completely to a standstill. only areduction in the output of the pump is effected. In this case the starting switch is regulated, in correspondence with the pressure in the receiver, in such a manner that when the maximum pressure is attained it reduces the speed of the driving motor and when the pressure falls the motor is again driven at full speed.

A constructional embodiment of the new controlling apparatus is illustrated, by Way of example. in the accompanying drawings, in which tor.

Fig., 1.is a diagrammatic view ofthe com.- plete installation in tfiCOl'lStlllQtlQhfil example as adapted for the purpose of bringing the pump or the compressor alternately a complete standstill and againto full speed. Fig. 1' is a similar viewof the pparatus asm'odified for reducing the output'of the pump or compres or whe t i mi l 9. a s de ,view'of thiis pist'on andi g Fig. 10 a. pl, n of the fr'o nt walhof the casing of thej v alve which is also, provided with controllingopenings.'-v

Referring to. F ig. 10f he drawings ll-isia compressor, the pressure .sideof which is connected by. means of the pipe 12 with. a receiver 13 which is to be supplied b the compressor. The compressor 18 provi ed at 14 with a fluid pressure actuatedunloading valve (not shown) of a type well known in the art which isgso arranged that when the valve is loaded by compressed air the compressor unloaded, while when the load on the valve is diminished the compressor operates and delivers the compressed air to the receiver 13. The compressor 11 is. driven by means of an endless belt 16 from an-electric motor which, in the example illustrated, is a three-phase motor. The stator windings of the motor 15 are connected to the mains 20 by means of the conductors 17 throu h an automatic opening and closing switc 18, which is controlled in a manner to be hereinafter described, and through a circuitbreaking switch 19. A starting switch 22, of a type known per se, which is connected by means of the leads 21 to thewinding of the rotor serves the purpose of starting the mo- The starting switch possesses three groups of starting resistances .23 and a bridge 24 which is movable over their contacts. The bridge 24 is fitted on an endless chain .25 which runs on two chain wheels 26, 27 which are fitted on the shafts 28 and Y29. The shaft 28 is in connection with an oil brake which is so arranged that the move ment of the bridge 24 for disconnecting the resistances 23 is retarded, while a retarda tion of the movement for inserting the resistances in series in the circuit does not catingoil mar-a low-lying storage conaine t0 a ed. c n ain r 32 from which the enis ondiitedtti those 'parts'of .the. machinewhich requi i e t0. be lubricated.

Ade tail description of th'isdevice is unnecessary since itforms. no partpof ;the invention.-

. The-sh iii-E2915 connected by means of .a second. chain drive, wh chconsists of a chain less chain; 33 and; thewheelfi i, with a .driv- ,ing, shaft .35. for, the starting switch .22. j The s a 3 s e yest a a pe a ov n .the previously nention ed openingigahd clos ing,sw iteh,18 ,.which,is connected .with the shaft- 35, in such-fa manner that it. is closed by the rotation.ofstheilatteriiilthe direction of the arrowig; befor.e;the,;bridge 24 of the start =ing switch 22 abegins to cut .out. the .resistanceswhile, in thewopposite direction of rotation of the shaft 35,-the switch -18 again openedaafterthe starting switch 22 has been moved back into its-.original position in which the wholegofthe'resistances .23 are connected in thescircuit, In the; drawingit has been assumedfor the sake of simplicity that the shaft 35 is .connected with the switch 18 by ..means of a =crankp36, which runs loose for a portion ofits pathway, and a connectingrod 37, but other suitable means for. thepurpose maybe employed.

The shaft 35,' ca'rries ,in addition to the chain wheel 34 and thecrank 36 or other device for themovement.of.,-.the,starting switch 22 and the switch 18,21 locking disc 37, of. which a more detailed description is hereinafter. given, a rope pulley, 38 and a toothed wheel 39. Round the pulley 38 is wound a rope or other flexible tension member 40 of which one end is fixed to the pulley 38, while the other end carries a weight 41 which tends to rotate the shaft 35 in the directionof the.arrow m, that-is, to rotate it in such a manner that the switch 18 is closed and the bridge 24 of the starter 22 is moved in the direction for disconnecting the resistances 23, that is to say it is moved downwards. With the toothed wheel 39 on the other handthere meshes a rack 42 which is fixed to the piston rod 43 of a piston 44 fitted in a cylinder 45. The upper end of the cylinder 45 possesses an inlet and outlet 46 for the compressed air. WVhen compressed air is admitted to the cylinder 45 the piston 44 moves downwards whereby the shaft 35 is rotated in opposite direction to that indicated by the arrow 9;, so that the bridge 24, through the agency of the chains 33 and 25, is moved insuch a way as to cause resistances 23 to be connected in series in wheel, behindthegwheeljztand not visible in the draw ing,.titted.-on the shaft '29, the'endthe circuit. .When the pijston- 44 has reached' its lower end position it is retained inthis position by the pressure medium.

Theinlet and outlet .46 otfthecy1inder 45' is controlled by a valve 47 which also serves the purpose otcontrolling the admission of pressure medium .to the unloading valve 14 .of the compressor 11. The valve 47, which has been illustrated separately Figs. 21(), possesses a casing '48 and a 'i "otary valve-49 'fitted therein, The "valve 491s, f por jtion of its length, tightly'journalled in a 'stutling -hox 50 of the j'casing' 48 'while its end acting againstitheother end ofjthe valve,

serves the purpose of secun ingtlre stufling o a flange 50 \v!th which 7 '25 it is provided tightly against lthe surface 48,

tightly against the front facet)?! of the easing 48. The spring 52 is supported with its outer end against a cap 54which is screwed Into the casing 48 and which simultaneously 110x501 and pressin of thecasing which 'may be"j )rovided with packing. The front surface of the rotary valve 49 whichfaces the wall 53 of the casing contains'a number of controlling channels. Thcre'are in this surface-two approximat ely radial grooves 55 and 56 of;l inited length the outer ends of which open-into the annularfspace 51 of the casing. Of these' the groove '56 is connected at its. inner end with a short arc-shaped groove .57 concentrlc tothe aius of rotation of the valve 49.

.There is provided also an approximately semi-circular groove 58, which is also concentric to the axis of the rotation of the valve, of wh ch one end is connected by means of a passage 59 passing round the groove 55 with an opening 60. Three openings 61, 62 and 63 provided in the front Wall 53 of the casing and arranged at about 120 apartcoact with the above-mentioned controlling channels and openings in the front surface of the valve. Of these openings the opening 62 is connected by apipe 65 with the unloading valve 14 of the compressor 11,

the opening 61 is connected by a pipe 64 with the pressure medium inletand outlet 46 of the regulating cylinder 45 for the starting switch 22, while the opening 63 leads to the atmosphere through an exhaust 66. In the. pipe 64 there is interposed a shut-off cock 68 which is however usually open and can therefore be neglected in the description of that part of the starting device which is, with respect to the operation of the apparatus as shown in Fig. 1, being dealt with. Finally the annular space 51 of. the casing 48 is connected by means of a pipe 67 with the receiver 13. so that the annular space 51and the grooves 55 and 56 connected with it are supplied with compressed air.

In order to relieve the valve. 49 from the axial pressurevvhich is-exerted upon ithy the pressure mediuni' pr inthe grooves 56 h.e$ 1aP 9f h Zi 3 ...u s deilhef lars'pace 51 is made such'ftliat thefend 49 containing the tcontrollin'g channels is of somewhat larger diam eter than the remaining portion of the valve. In thisffw ay there isfformed a smallishoul tlen 49 which is also subject to the pressure of [the .pressure; me.-

-diurn in thejan'nlulars 'pace :51 hilt in the-opposite direction, to that] of the pressure on theend surfactant j that the two axial pressures neutraliseone graves :5 156i another, In practice theiarea hf, the annular surface at thesl o'ulder'4 9 rnays ueh that the 'valve 49fwill he pres sed tightly against the front wall of casing 48 hy. the pressure acting on I the ,ls'hoi ldenin .which case thespring 52 only serves the" purpose of pressing the valvef49 against the-front ..5 w en masses: is not p e The controlling cha li 'els in lthe valve-749 findin openingsfi iri the time ivanjziapraw casing are so arranged with respeet .to .one another that threeflifterent conneetiorislare produced in ,umrarwnmamc p'o'sition'sfof the valve. 49. Namely, in the-end position illustratedin Figs. 1,,2and 2 which is the.

position of rest, the annular spaee51 of the vcasing 48. is .co nnected by, means, of .the

grooves 55, 56 'a"nd-. 57 withthe' 'openings 61, 62, so that the pressure, medium coming froin'the receiver 13th'rou'gh the pipe '67- flows along the pipes 65 and 64 to theunloading valve 14 of v"the. compressor 11 and into the cylinder 45 of the starting: switch 22. In the middle position illustrated in Figs. 3 and 3*, on the contrary, the pipe-64.

leading to the cylinder 45 is connected through the opening 61. the groove 58. and the exhaust 66 with the atmosphere, while the unloading valve 14, owing to the areshaped groove 57 being connected to the groove 56, remains connected with, the collector 13. In the end position, as illustrated in Figs. 4, 4 (the so-called operating position) on the contrary, in addition to the cylinder 45, the unloading valve 14 is also connected with the atmosphere, namely by means of the openings 62. 60, the passage 59, the groove 58 and the exhaust 66 and is thus relieved from pressure.

The end 49 of thevalve 49 is provided with a shaft 69 which passes out through the front wall 53 of-the casing and has a quadrangular outer end 69. On the quadrangw lar end 69* of the shaft there is fixed a doublearmed lever 70, 71 which serves the purposeof rotating the valve 49. The douhle-armedlever 70, 71 is of a hollow construction, that is to say it consists of a tube. in which two balls 79, which serve as loading weights, are arranged. These balls, when the lever is inclined, fan run from of' completing" the movements which have been initiated by other means. Thelregula-Q tion of the valve 49 'is effected in part .elec- -trically and in part by mechanical means. For the purposes of the electrical adjustment there is arranged a magnet coil 72 the armature 73 of which is connected by means ofa'rod 74 with the valve lever 70, 71 in such'a manner that it has a certain'amount of free movement. The loose coupling consists in this case of a 'pivot75 provided on the rod 74 and a slot 76 which runs at an angle to thelever arm 70 and is made in a downward extension of the arm 70, in

' which slot the pivot 75 of the rod 74 engages. -If. in the position of rest of the valve "47"illustrated in Figs.'2, 2, the armature 73 of the 'magnet js attracted the rod 74, after a short free movement, then carries the lever 70, 7lflwit-h it and thereby rotates the valve 49 into the'middle position illus- ,trated in Figs. 3, 3. The movement of the armature 73 when attracted by the magnet is'limited by means of a stop 73* provided on the armature. The mechanical adjust ment consists on the other hand of an arm 77 fitted on the shaft 35 of the driving mechanism of the starter 22, which arm, whenthe shaft 35 is rotated in the direction of the arrow :17. knocks against a projection 78 provided on the arm of the lever 70, 71 and therefore turns the lever further in the same direction in which it was previously rotated by the armature 73. The arm 77, however, does not effect the whole of the rotation of the valve into the end position illustrated in Figs. 4, 4, on the contrary, it only rotates the lever until it takes up an inclined position such that the balls 79 which were originally in the lever arm 70 can run into the arm 71 the result of which is that the centre of gravity of the lever 70, 71 is displaced to the arm 71 and the lever is now rotated by the action of gravity completely into the end position illustrated in Figs. 4, 4. In addition to moving the valve 49 out of the position of rest of Figs. 2 and 2 into the middle position of Figs. 3, 3 the electro nagnet 72, 73 also serves the purpose of returning the valve from the end position of Figs. 4. 4 into the. position of rest. For as soon as current ceases to flow in the magnetcoil 72 its armature 73 falls down again, the rod 74, again after a certain free movement. carries the lever 70 71 with it and thus ro- (ates the valve 49 in the opposite direction to that in which it was previously rotated. In this case as soon as the lever 70, 71 takes up approximately the inclined position illustrated in Figs. 3, 3' the balls 79 roll back again into the lever arm 70 and the remainder of the rotary movement'ot the valve into the position of rest, which-cannot beeflected by the armature 73 owing to its initial free movement, is brought' about by the weight 'oflthe balls. L

The electro'magnet 72, 73 finall serves the .purpose also'of controlling a loc ing de vice. This consists of a disc 37 which, as previously mentioned, is fitted on the shaft 35 of the operating mechanism of the starting switch 22. a catch 80 pivotedabou't a fixed point and a lever 81 pivoted on the disc 37. The lever 81 is bent to the shape of an arc of a circle and one end is revoluble about a pivot 82 fixed to the disc 37. The free end of the lever carries two projections 83, 84 which he one behind the other when seen in the direction of rotation of the disc 37 and are for the purpose of coa'cting with the catch 80." The lever 81' is always rotated outwardly by means of a spring which is: fixed to the disc 37 and isr-not illustrated in the drawing into a position such that not only the projections 83,184 but also a part of the lever itself projects beyond the edge of the disc. In the 'positionof the shaft 35 and the disc 37 illustrated in Figs. 1, 2, 2'

the projection 84 of the lever 81 abuts against the catch 80, whereby the shaft 35 and therefore the whole operating mechanism of the starting switch 22 andtbe switch 18 are prevented from rotating in'the direction of the arrow :v. The release of the locking device is effected by means of the. elect-ro-magnet 72, 73 throu h the agency of a double-armed lever'86. 8 which is revoluble about a pivot 85 which is fixed in position. One arm 86 of this lever serves the purpose of rotating the locking lever 81 inwardly relatively to the disc 37 while its other arm 87 is so placed relative to the armature 73 that it extends between two transverse studs 88 provided on its rod 74. When the armature 73 falls the releasing lever 86, 87 takes up a position such that the lever 81 can be held by its spring in the locking position in which the projection 84 engages with the catch 80 (Figs. 1 and 2). If however the armature 73 is attracted it then rotates the lever 86. 87 in the direction of the arrow 1 (Fig. 2) whereby the locking lever 81 is rotated inwardly relatively to the disc 37, so that the projection 84 is released from the catch 80 and the shaft 35 of the starting mechanism can. be rotated in the direction of the arrow 2:.

The magnet-coil 72 which is constructed as a voltagecoil is connected in shunt with the motor circuit. and is connected by the leads 88, 89, 90 in front of the automatic switch 18 to the two phases R and T of the main supply to the motor 16. In the auxiliary circuit of the magnet-coil there is inserted. on the one hand, a hand-operated switch 91 whereby the auxiliary circuit can be opened and closed at will. In the osition 1 of this switch 91 indicated by full lines in Fig. l of the drawings the auxiliary circuit is opened, while in position II illustrated by dotted lines it is closed through the switch blade 92 and the contact 93. The

' auxiliary circuit of the magnet contains on the other hand an automatic opening and closing switch which consists of two contacts 94, 95 and a bridge-piece 96. The operation of this automatic switch is dependentupon the pressure in the. receiver 13. To this end the bridge-piece 96 is fixed at the outer end of a plunger 97'which is guided in a cylinder 98 and is-insulated from the plunger. This cylinder 98 is connected by a branch 67' to the pipe. 67 and by the latter to the receiver 13, in such a manner that the pressure medium conducted to the lower side of the plunger.97 tends to open the switch 96. The movement of the switch in the opposite direction on the other hand is effected by a spring 99 which is located in a casing 100 which is formed on the cylinder 98. One end of the spring 99 is fixed to the plunger 97 while the other end is supported against the cover of the casing 100 which is suitably adjustable for the purpose of regulating the tension'of the spring. The tension of the spring 99 is so adjusted that the pressure acting on the plunger 97 holds the switch 96 in the open position if and so long as the pressure of the compressed air in the collector 13 does not fall below a predetermined value, for example, 4 atmospheres. As soon, however, as the pressure falls below this value, for example below 4 atmospheres, the plunger 97 is moved downwards by the spring 99 against. the action of the air pressure in the cylinder 98 and the switch 94, 95, 96 is thereby closing. W hen this happens current flows through the magnet-coil 72 and the armature 73 is attracted with the result that the valve 49 is operated and thereby starts the compressor 11 in a manner to be here inaftcr described in greater detail.

The magnet-coil 72 connected to the two phases R. T of the supply mains forms also a no-voltage coil which watches whether the voltage is maintained in these two phases. If the voltage fails the armature 73 cannot be lifted upwards and it is therefore impossible for the valve 47 to be set in a position in which it starts up the compressor 11.

If the armaturc 73 has already been at tracted upwards then. when current ceases to flow through thc coil 72. it falls downwards and rotates the valve 47 back into its position of rcst. In order further to keep a watch on the third phase S, an automatic switch-consisting of the contacts 101 and the iliary bridge 102 is also arranged in the auxiliary circuit of the magnet coil. 'lhc bridge 10;! of this switch is fitted on the armal'ure 10:5 of a voltage coil 104. This coil lthl'is connected by the leads 105, 106 and S9 to the phases 5 and T of the supply mains. lts circuit can also be opened and closed by the hand-operated switch 91, as follows. When the circuit of the magnet coil 7:2 is closed the circuitof the coil 104 is closed through the second switch blade 92 and the contact 107 while, on opening the circuit of themagnet 72 the circuit of the relay 104 is also opened. Owing to the arrangement of the no-voltage 'relay-t .he result is obtained-that when there isf a failure of voltage in the phase S only thecontrolling magnet 72 of the valve 47 is without current since the-auxcircuit of this magnet is broken by the switch 101, 102. 4

Finally, in order to automatically discon nect the magnet-coil 72 if the current should become greater than is permissible owingto a short circuit .or similar reasons,-two ;'further circuit breaking-switches 108,109 are arranged in the auxiliary circuit of the coil 72. closed by means of a spring 110, they can however be opened by two magnets 111. The coils 112 of these two magnets 111 are directly connected to the twophases R and T of the leads to the motor and they are constructed in such a manner that, if a short circuit or similar rush of current takes place, they attract the armatures 113 which carry the contactbridges 109 and thereby break the auxiliary circuit of the magnet 7:2... The switches 108, 109 are held in-rthe open position by two catches 114 which must be released by hand. when-the switch is to be opened again after the short circuit or other disturbances which'caused =an unpermissible increase in the strength of the current, has been put right. i

The method of operationof the hereinbefore described apparatus is as follows.

Let it be assumed that the receiver 13 has been partly tilled but that the pressure is not. sufficient to hold the switch 96 in the open position against the action of the spring 99, so that this switch is closed. If now the hand-operated switch- 91 is mr'ircd'into the position 11, that is,/ is closed, then, on the one hand, the circuit of the magnet coil 72 is partially connected up thrpugh the switch blade 92 and the contact 93, and on the other hand the cireuit'ot the voltage relay These switches are usually held ill I 101 is closed through the switch blade 92- pressor -11-is, connected-; through the opening .62 and the grooves 57,156; with the-annular space 51 of thecasing 48, which is itself in i connection through the pipe- 67 with the receiv'er 13, so that the valve 14 is placed under pressure and unloads the compressor'll. On the other hand the pipe 64 leading to the regulating cylinderof the starting switch is connected b way of the opening 61, the groove 58 an the; exhaust 66 with the atmosphere, that is to -say, it is relieved from pressure. The shaft 35is consequently rotated by the weight 41 inthe directionof the arrow :10 andraisesthe piston 44 in=so doing. As this takes place the switch 18 is first closed whereupon'the bridge 24, moving downwards, gradually cuts out the resistances 23 until the motorv 15 and the compressor 11.which is driven by it and is at this time unloaded are making their full number of revolutions. As soon as the starting switch 22 reaches its end position the arm 77 carried by the shaft 35- engages the projection 78 on the adjusting lever 70, 71 of the valve 49 .and thereby effects the rotation of the valve49 into the position illu' strated in Figs. 4, 4*, which rotation, after -of the lever into the arm '71.

the lever 70, 71 has been inclined to a certain angle, is completed by the weight of the balls 79 which run out of the arm 70 In the end position of the valve 49 illustrated in Figs. 4, 4 not only does the regulating cylinder 45 of the starting. switch 22.remain connected with the atmosphere but the pipe leading to the unloading device 14 of the compressor 11 is now also connected to the atmosphere by way of the openings. 62, 60, the passage 59, the groove 58 and the ex haust 66. That is to say the valve 14 is now also released from pressure so that it loads the compressor 11. The compressor which has been meanwhile driven at' full speed therefore now compresses air into the receiver 13 which is thus again charged. \Vhen, owing to the receiver being completely charged, the pressure in it reaches a predetermined maximum value the load on'the plunger 97 has been increased to such an extent that the plunger can be displaced against the action of the spring 99 by means of the pressure medium introduced into the cylinder 98. The switch 96 is thus opened and breaks the circuitof the magnet-coilon'the other hand,-through the 72 which therefore allows the armature 73 to fall down. The falling armature on the one hand returns the releasing lever 86, 87 of the locking device to locking position and, a ency of the rod 74 it carries the adjusting lever 70, 71 of the valve with it and thereby initiates the return ot'the lever into its original position or position of rest as illustrated in Figs. 1, 2, 2. This movement is again completed by the. weight of the balls 79 since; after thelever 70, 71 has been inclined to a certain angle, they run into the arm and thereby load the piston of the valve in-such a way asto rotatejit backwards. Owing to the rotation of the valve 49 into its original position-the pipe-65,1eading to the unloadmg valve14 isafirst'connected b way of places the unloading 'valve under pressure,

that-is to :sayothecompres'sor 11' is again unloaded and-the pipe'64 is finally connected with the annular space 61 by way of the passage '61-and the 'groove 55, so'that compressed -air' again flows into the regulating cylinder 45. 1 The-compressed air moves the piston 44 into its lower end position whereby the shaft 35 is rotated in the opposite direction to that indicated by the arrow-a: by means of thefl'rack and pinion mechanism 42, 39. When this: takes place the-starting resistances 23 'arefirst a ain connected in series in the-circuit and t en,'owing to the opening of the switch 18, the motor 15 is disconnected from-the mains 20. Vhenthis has occurredthe shaft 35 is again held fast in' the position illustrated in Fig. 1 owing to the catch 80 coacting with the projection 84 on the lever 81 of the locking disc 37. The motor 15 and compressor .11 are now unloaded. The starting device now remains at rest as long as the pressure in the receiver 13 does not fall below a predetermined limiting value. If, owing tothe withdrawal of 72 is a ain closed by the spring 99 and the aboveescribed action is repeated. The compressor, as will now be clear, is always unloaded and develops full speed before it is'loaded and, conversely, on again disconnecting the driving motor'the compressor is again unloaded and comes to a stop.

The same action however, also takes place whencurrent ceases to flow in the motor owing to failure of the voltage or if a short circuit or similar electrical disturbances occur. Assume for example, that the. compressor has been started .inthe manner previously described and is now running fully loaded. It now the voltage in one or all of the phases fails or a short circuit occurs the magnet-coil 72 either becomes imthe locking device for the shaft 35 fitted on the disc 37 is released in the 'nianner previously described and the valve 49 is simultaneously returned to its original position or position of rest,so that the valve 14 on the one hand and the regulating cylinder 45 on the other hand are again subjected to pressure. The motor- 15 is therefore disconnected by the starting switch 22 and the switch 18 and the-compressor '11 unloaded, after .which the shaft is finally held fast in' the disconnected position. The; result is the same if the circuit of the magnet-coil is purposely broken by'hand by means of ,the switch 91. Thus, in all cases the starting switch is returned to its original position of rest,- nnd locked in this position, so that on the return of the voltage or'on rerconnecting the magnet circuit the driving motor 15."1s

started properly while'the compressonn is unloaded. If th disconnection of the dl'l? ing motor has been'due to failure of the voltage the, startin' procedurejtaltes place entirely autumatica ly when the voltage returns and no special switching by hand is necessary." T he new device therefore gives the greatest possible security in operation and requires very little attention and faulty -operation of the apparatus, for example starting up the compressor under full load, is quite out of the question even it electrical disturbances have occurred] The new controlling apparatus can, ac cording to the invention, also be so con"- structed that, when a maximum pressure is attained in the receiver 13, the driving motor 15 and the compressor I11 are not brought absolutely toastandstill but run at a lower speed and therefore produce a smaller output. In this case the above. described installation is augmented by the devices illustrated in Fig. 1. These are, firstly, in addition to the regulating cylinder 45, a second pressure medium cylinder 115 for the return of the starting switch 22. In this cylinder 115 there is again fitted a piston 110 the piston rod 117 of which is formed as a rack. The rack 117, the object of which also is to react with the pinion 39. is however sinnewhat shorter than the rack 42 so that, on the one hand, in the lower end position of the piston 116 it does not mesh with the pinion 39 and, on the other hand. it can only partially rotate the shaft 35. namely about an angle in the opposite direction to that indicated by the arrow .0 such that the starter 22 can be returned from the full speed position to the position in which a port ion of the resistances 23 corresponding to the desired reduced speed is inserted in'the circuit, while the opening and closing switch 18 on the contrary remains connnected. The second re ulating cylinder 115 is controlledbya'va ve 1182 This valve is for" the most part arranged similarly to the valve 49 but is however constructed as a simple reversing valve, namely, in such a manner th'at in its position of rest it connects the upper end of the re nlating cylinder 115 by wa of pipe .119 with an exhaust 120 leading to the atmosphere, and

the. lower end of the cvlinder by way of a pipe 121 with a branch (i7 of'the pipe 67 leading to the collector 13; In its ,other end position the valve 118 efl'ects'the reversed connections, that is to say the pies sure medium then flows by way of the pipe H9 above the piston 11G in'the'cyliiider'II5 while the space below the piston 116 is connected by way of the pipe 121 -withtheatmosphere. 'The piston 116 of the cylinder 115, in addition to rotating'th'e shaft 35, also serves the purpose o fiadjustir'i'g' the previously mentionedtshut o ttcock 68 which is arranged 'in the pressure piping 64 of the regulating cylinder 45. 'loth'i's' end two lateral stops 122, 1223 are titted on'the rack 117, of which the upper'dilil 'opens'tlie cock 68 when the piston 116 moves downwards while the other closes the cock (SSQwhenthe piston moves in the reverse direction. f

The reversing valve 118 is regulated exclusively by elcctricity,-aud for this purpose there is provided a magnet-coil 124 the. armature 125 of which is connected by means of a rod 126 with a double-armed vlever 127, 128 titted on the shaft of the te- -t ary pistop of the valve 118 in such a man- ,ne'r. that, Wm-Lig- :.irmature 125 is attracted,

the valve 118 is rotatc'ttput of the position of rest illustrated in the"dra'wing into' the V opposite end position, and, chop the arnia turc 125 falls, is again rotated into the position of rest. This rotation is only initiated by the armature 1:15 and is completed on the contrary by a weight. which runs altcrnately from one arm of the valve lever 1'17. 128 to the other arm. consist, as in the valve 40, of balls guided in the. hollow lever; I In the position'Il of the hand switch, that is to say, when the starter 22 is controlled by the valve 49 and the regulating cylinder 45, the magnet-coil 1:24 is, on the one hand, connected by means of the conductor 88, the contact 413, the switch blade 92 and the conductor 89 and on the other hand by a romlurtor 131 and the conductor 90in parnllcl with the magnet-coil TL and the switch ill. 9(3 to the two phases 1t and T. The (oil 124 therefore in this case always has the voltage applied 'to it. the consequence of which is that thc arnniture 1:25 is attracted and the valve 118 is so adjusted that the pis [on no is held fast in its lower end position by the pressure medium introduced into the This weight may top of the cylinder 115, so that the rack 117 remains inoperative and the cook 68 is open. If, however, the hand-switch 91, which is constructed as a reversing switch, is rotated into the position III the magnet-coil 124 is then laced under the control of the pressure switc i 94, 96, while the circuit of the lnagnet-coil 72 is in parallel to the switch 96. In the position 111 of the hand-switch the circuit of the coil 124 is as follows. The current flows from the conductor 90 along the conductor 131 to the upper end of the coil and from the lower end of the coil across the switch 94, 96 through a conductor 129, the contact 130 and the switch blade 92 to the conductor 89. The magnet coil 72 on the other hand is connected firstly through the conductor 90, and secondly through the conductor 129, the contact 130, the switch blade 92, and the conductor 89, independently of the switch 94, 96, to the phases R and T. In the position III of the hand switch 91 the circuit of the voltage relay 104 is closed since the switch-blade 92" connects to an auxiliary contact 132 which is connected with the conductor 106.

The method of operation of the augmented apparatus is as follows.

Assuming in the first place that, when the hand-switch has been placed in the position II, the motor 15 is started and runs at full speed while the compressor 11 is unloaded and is then loaded in the manner which has been hereinbefore described in detail. WVhen this starting procedure has been completed the hand-switch 91 is placed in the position III, that is to say the circuit of the coil 124 is closed through the switch 94, 96 and the circuit of the coil 72 on the contrary is closed independently of this switch. Since the coil 72 now has the voltage always applied to it, the valve 49 remains in the Operating position of Figs. 4, 4 in which the regulating cylinder 45 and the unloading valve 14 of the compressor 11 are relieved from pressure, so that the switching of the starting switch 22 can be now effected by the second regulating cylinder 115. If now the pressure in the receiver 13 reaches the maximum value at which the switch 94, 96 opens, the magnet-coil 124 is then without current and the falling armature 125 rotates the valve 118 from the positio'n in which the upper side of the piston 116 is subjected to pressure into its other end position. The space above the piston 116 is therefore connected with the atmosphere while compressed air enters from the bottom into the cylinder 115 and drives the piston 116 upwards. The shaft 35 is thereby rotated in the direction opposite to that indicated by the arrow .1, owing to the rack 117 meshing with the pinion 39 after a short inoperative movement. and the bridge 24 ot the switch is returned to the required position for a reduced speed,

that is a portion of the resistances 23 is connected in series with the winding of the rotor 15 and the compressor 11 runs at a reduced speed. If the quantity of pressure medium withdrawn from the collector 13 is greater than that delivered by the compressor when running at the reduced speed the switch 94, 96 will be again closed, after a certain interval of time, by the spring 99. The armature 125 then being attracted reverses the valve 118 so that the space under the piston 116 is again connected with the atmosphere and compressed air on the other hand enters the space above the piston 116. The shaft 35 is consequently rotated in the direction of the arrow a: partly by the rack 117 and partly by the weight 41, whereby the resistances 23 are entirely disconnected so. that the motor 15 and the compressor 11 again run at full speed. 7

Also when employing the apparatus as a revolution or output regulator',-care is taken to ensure that if electrical disturbances occur the switch 22 is always returned to its original position, that is to say the resistances 23 are connected in series. If, for instance, current ceases to, flow in the magnet-coils 72, 124 when the driving motor 15 is connected so that it is running at full speed, then both the valves 49 and 118 are returned to the position of rest by the falling armatures 73 and 125, the consequence of which is that the switch 22 and the switch 18 are returned to the position of disconnection by the piston 44 of the regulating cylinder 45'and are held fast in this position by the locking device on the disc 37, If an electrical disturbance occurs when the motor and compressor are connected so as to run at a low speed, that is when the piston 116 of the cylinder 115 is in its upper end position, then only the catch on the disc 37 comes into action and, owing to the coaction of the projection 83 of the lever 81 with the catch 80, holds the shaft 35 and the switch 22 fast, the resistances 23 having been connected in series, while the switch 18 remains open. In the upper end position of the piston 116 the cock 68 inserted in the pressure pipe 64 of the cylinder 45 is closed by the stop 123 on the rack 117, so that the pressure medium cannot flow into the cylinder 45. This closing of the rock 68 is necessary to prevent damage to the rack and pinion mechanisms 42, 39, 117 and the cylinder 115, which might otherwise occur if the cylinder 45, of which the piston 44 has a longcr stroke than the piston 116 of the cylinder 115, were subjectedto pressure in the upper end position of the piston 116. If the apparatus has been closed down or shut off from air pressure when the starting switch 22 is inserted but the switch 18 is open then, when the magnet-coils 72 and 124 are re-excited,

re-starting takes place since pressure medium is admitted above the piston 116 intothe cylipder 115 and the -s ace-below the iston '116"ts.-.;- oi1 the other" land, con 5 nected with the atmosphere,'while the pis tonjlfl in. the cylinder is free from load. 'In'the lower end positionof the piston-116 the co'ck'68 is again opened so thatthe cyl-' inder 45, the regulating valve. 49 git-which has again moved into its operating end 110- sitio'mas. shown in Figs-4 4-, when start.- ing occurred-,isaglain readyto efi'ect discon- I nection j should 1 any electrical disturbances .s' cc'urif l chemise; fiodim'ent illustrated are possible without departing' -fmm the" s'pirit of :the invention. particu-lar," .the devices "which have only bananas-mated more or les's diagrammat iland-'1 couldin 'practice-be const .-.4rasriewccncm11ing apparatus is --.not limited employment with th1ee phase'c-urrent,-it 'Q d,f .;eu" seal b e pl y d" i a .3 ump-or omp essor driven -by"a'--dire ct or. alternating-current motor. In-J'this casc the 'specialno voltage relay l04fas-well as one of. the overload relays are unnecessary. @I claim: In an automatic-Econtrolling apparatus .jfor ffluid pressuresupply systems, the combiiiation ofa compressor and 'an'elec't-ric'mo- "tor ior driving ,the'i'sam'e, a" motor-circuit, a

fcontro'lli-ng the 'supplyjof current ,and f u'nlolidi-ngi" device. and fluid pressure responsive 'felectro mechanical means .includ- 'j- 4 and simultaneously governing the-"compressor loading and unloading device for compressor loading and unloading actions.

2. In an automatic controlling apparatus for fluid pressure supply systems, the combina'tion of a compressor and an electric Y motor 'for driving the same, a motor circuit, ,9. switch controlling said circuit for motor starting-and stopping actions. a device 1110- 'chanically operated in'o'neidirection and I fluid 'Ipressurc operated in the'reverse dircc tion for shifting thevalve respectively in starting: and stopping directions, a loading and inloadin'gde vice; lOCkiDgI means for normally holding the switch actuating device from operation, a control valve movable"in one direction to place the loading {Hid unloading device in unloading condi-- tion and thefluid pressure actuating means ofthe switch operating device in condition to perini-t'said switch operating device .to be {operated in one direction by its mechanical -m ean s,and said valve being movable-in a reverse direction to place the loading and unloading ,device in loading condition and "to cause actuation of the fluid pressure opma'ny alterations 'of the enierated means of the switch operating device to return said device to. normal position for a current c ut out actionofthe switch, fluid presure respoiisiye electricalmeans gfor moving the control valve in the first-named direction, and means actuated by the fluid pressure operatinv means .of theswitch actuating device an 'with the'latter .for movingthe control valve in the second-named direction. .3. In an autom tic controlling apparatus for. fluid pressure supply systems, the combination of a compressopgnd; up electric motorfor driving the same, a man ljtjlfgu it,

for fluid pressure supply systemszt main pressorloading and unloading device, ;fluid pressure responsive combined electrical and mechanical means,inc l,udi ng a, control valve for placing the loadingrand unloading device inainloading and loading conditions and simultaneously actuating. said-switches for current --supplyin g and cut out actions, .said means operating to move the starting switch eon its current feed motion after the primary switch has been closed and to move the starting switch back to initial position prior to the opening of saidrprimary switch.

5. In an automatic controlling-apparatus for fluid-pressure supply systems, the combination of a compressor and an electric motor for driving the sameyu motor circuit. a resistance Starting switch in said .motor circuit, a compressor loadingand unload in; device, a switch actuating device, mechanical means for moving said switch actu ating device in one direction. fluid pressure operated means for moving the switch actuatin; device in the reverse direction. a cow trol valve movable in one direction to place the loading and unloading device in unloading condition and .to place .the fluid pressure actuating means for the switch actuating (h vice in condition to permit said device to he operated by said mechanical means. fluid pressure responsive electrical means, for-movingthe control valve in the first-named direction, and means operable by the switch actuating device for moving the control .valve in the second-named direction.

6. In an automatic controlling apparatus dua o d ng. d vice a mmbtnation of a compressorand a-neleetlzi'cimetb for driving the same,--a motorcircuit, we =cireuit .:a-p rimary swi-tch in the main circuit,. a starting switch in the. motor circuit, a comfor fluid pressure supply systems, the combination of acompressor and an electric motor for driving the same, a motor circuit, a compressorloadin and unloading device, a rmistanceps'witch in the motor circuit," a switch actuating device movable in reverse directions to actuate the switehfor currentsupplyingand 'cut ofl actions, mechanical means for moving the switch actuating device in one direction, fluid pressure operating means for moving the switch actuating device in the opposite direction, locking means "for holding the, switch actuating device from motion under' the action of "its .meclnmical actuating means, a control valve movable in one direction-to place the loading and unloading device'in unloadingkondition and to place'the fluidpi'essureactuating means of the switch "actuatingdevice in c'onditioii to permit operationjt-hereof by said mechanical means, and said valve being movable in the reverse direction by the switch actuating devi'ce'in t-he dir cction of motion imparted by its fluid pressure actuating means for supplying fluid pressure to said-fluid pressure actuating means andplacing-thc loading and unloading device in loading condition. and

- a fluid pressure responsive electrical device cal means for rotating said switch actuating device in 'the fiist-named direction, fluid pressure actuated means for rotating said switch actuating device in the econd-named direction a control valve movable in one direction to place the loading and-unloading device. in unloading condition and to place the fluid pressure actuating meansof the switch actuating device-in condition to permit actuation of said device by its meeha=ni cal means, and said valve being movable in the reverse direction to place the loading and unloading device in loading condition and'to supply fluid pressure to the fluid pressure actuating means of the switch actualing device for switch actuating open-xtio'n by aid means,- a locking means for holding the switch actuating device against actuation by itsniechanical means, fluid prcs ml. re ponsive electrical means for releasing said actuating device and movingthc control valve in the first-named direction, andmeans operable" by andanovahle' with "lheswilch actuating device on its actuation by its fluid pressure means for moving the control valve in the second-nameddirection.

8. In an automatic controlling apparatus for fluid pressure supply systems','the combination ot'a compressor and an=electric motor for driving thesame, .a motor circuit, a resistance starting *switeh in said circuit; a loading and 'unloading'device for thecon'ipres -or, a switch actuating device movable in one direction 'by mechanical means to actu ate the SWltLlllll one-direction and movable in the reverse direction by fluid pressure operating means foractuating-the switch-in the opposite direction, a control valve movable in-on'e direction by the switch actuating device -fo r supplying fluid pressure -to said fluid pressure actuating means and placing the loading and 'unloadin condition and said valve fleing movable ina reversedircction to place the loading and unloading device in unloading condition and said-fluid pressure operating means in con-- dition to permit actuation of the .valveactuating device-by its' mechanical means,.and fluid pressure responsive electrical means for moving the control valvein the -seeondnained direction. a -i m 9; In an automatic controlling apparatus for fluid pressure supply systems, the combinationof a conipressor-and an electric motor for driving thesame, a motor circuit, a resistance startingan'd-stopping switch-in said circuit; an auxiliary circuit containing a control switch, anelect'ro ina'gnet in said auxiliary circuit; a switch actuating device movable in= opposite directions for current supply and cut out movements'o'f the'switch; mechanical means for -actuating said switch actuating device in one direction, fluid pressure operated "l11 l'IlS for --actuating said switch actuating device in the reverse direction, a compressor loading and unloading device, a locking means for holding the switch actuating devicefrom movement in one direction, a control valve movable ;in reverse directions for-governing thedoading and unloading device and the pressure actuating means of .theswiteh actuating-device. means operatedby the energiiation of the =electro-magnet for releasing'the locking meansandmoving said valve in one direction,-.and means actuated by the valve-actuating device forinoving said control valve in the opposite direction. s 10. In an automatic controlling apparatus for. fluid pressure supply systems, the combination o f'a compressor-and an' electric motor for "driving the same, a' moto'r'eircuit', a resistance starting and stopping switch in said circuitaswitch actuating device mov able in opposite directions to move the switch in opposite directions, a loading and unloading device for the compressor, me-

. chemical means-for moving the'sWi-tch aetu ating device in one directiomfluid pressure device inloading 7 lit ito

operatedmeans for m vingJthe. switch actu;

ating device in the opposite direction, econ-c,

t-rol' valve m'ovable inone: direction to place 7 theloading and unloading device in unloading conditions and to placetlie tlu id pressure actuating means -of-1the switch actuatof-"said 'switch actuating. device I by.-

means jfor 1 holding; the switch actuating viceafron'iaction byits..-mecl1anieal means, a fluxd pressure responsive means ncluding an.

electro-magnet, for; releasing lsa id locking meansi andmoving-a the control valve Iin ,thc. first-snamed directiomf'and means" operative by; the --valvev.actua ting djevic e on the motion of-t'he same byits mechanical. means; to shift. said valvein the; secondlnamed dircc tilont; -f-'.- r .15 1-1. An. automatic controlling apparatus in accordenfie with-clai-m l in hich the CltEQtliQ mechanical,- means. operates the valveand the motor circuit switch and comprises a ':ont;rblling circuit, an .electromag'net in said circuit, a valve actuating lever, a weight normally held fronianovement and released for movement by the energization of the magnetand operative on its working motion to close the i motor circuit switch and to shift the valve actuating lever for valve operating motion in one direction for a portion of its travel in such direction, an armature controlled by the magnet and operative to shift the valve actuating lever for valve operating motion in the opposite direction for aport'ion of its-travel in such direction, gravity means for coinpleting the travel of the valve actuating lever in either direction when initiated in one direction or the other by the weight and the armature, and valve controlled means for returning the weight to normal position and the switch to motor circuit opcning position.

12. In an automatic controlling apparatus in accordance with claim 1, in which the clec-' tromechanical means includes mechanism for operating the switch and valve. :1 control circuit, a control magnet in said circuit, an armature actuated by said magnet and operative to throw said mechanisn'i into action, a pressure actuated switch for opening andclosing said circuit, an overload relay for opening and closing said circuit. and a novoltage relay for opcnin and (losing said circuit.

13. An automatic controlling apparatus in accordance with claim 1. in which the electromechanical means includes a control circuit, a control magnet in said circuit, a mechanism for operating the valve and the motor circuit switch. a locking device for holding said mechanism from movement, and

an armature actuated by .the magnet when thehlttcr is energized to release the locking de 14.:Anaut omatic controlling: apparatus in accordance with claim 1, in which a starting switch isemplqv'ed inconjunction with the inotorcircuit switch and in which the electromec anical mcans includes a control circuit, mechanismfor operating the valveand the switches. .audelectronicchauical means in said cireui'tf -tarting' said mechanism into 1l t fil l i:\ l l(?i\ .he control fcircuitis closed, the

' uitfndlstar A iiiotor starting action 'l l b'e op"e1 ic upon the completionof the open ng :moveme'ntof the starting 5 V.

'accm-dance with claim' l ,"in"'which the control-valve comprises acasing having an end wall provided with controlling channels, and

.a rotary body having controlling channels at one'cnd, the casing being provided with a pressure receiving space surrounding the channeled end of the body and into which space some ofthe controlling channels of the body open. the said rotary body being so shaped as to provide a'shonlder adapted to be acted upon by the. fluid pressure so as to press the channeled end of the body against the channeled front wall of the casing.

17. An automatic controlling apparatus in accordance with claim 1. in which the control valve comprises a casing having a ported end wall, a rotary body enclosed in said casing and having, a coactin; portedend, and a spring-for pressing the ported end of the valve body against the ported end wall of the casing.

18. An automatic controlling apparatus in accordance with claim 1, in which the electromechanical means operates the control valve and includes a double-armed lever fixed on the shaft of the control valve. means for shifting said lever to a part way inclined position in either of its directions of movement and a weight mounted to roll from one arm of the lever to the other when the position of the lever is inclined to complete its movement.

19. An automatic controlling apparatus in accordance with claim I. in which the motor circuit switch is a variable speed switch and {dtightly against said front wall the electro'mecha'nichl means'c'perates acontrol valve and switch "and-comprises a"me= chanical device movable in one direction and to Adjust the "switch for a cii'rreut'siipplying action zind movible in the reverse direction for 'a djusting' theswitch'for a c'ui'r'entfcutqu t' action, a control circuit, angelectromag net in said circuit, an armaturezictuated by the ma'gnet' for shiftingthe valve *in the opposite dii e'c'tioh and 'for setting the "meehani'cal (levice 'intodperatieh to shift-the valve in the fiist-nanieil diljectien and adjust the switc'li'fiorciirrent supplying fiCfiOll,'.2l fluidlpresui'e (lei 'ice 'for 'ijetracting the mechanical device t6 shift the snitchto-cnt-cut positin'n a' secon'dffliiid Pressine' device for rctr acting the mechanical device to adj-list fthe'is wi tch" to a lew'speed 'cii' n'e-ntfc'erl' positi'ei'i, 'zi'sccend vzilvcfei"controllingthe sup ply of flnid pressure to render the first-named flnidfpressnre device "inoperative when the .seceigdii'amed fluidpreslmfe device is in action, second electrb'iiiagn'et', iin 'iirma tui'e influenced thereby Ifoiil'djustii-ig the secondn imed ii'alve, a switch f6r throwing said second-named electronm'g-nct"into and o uticf thje'coiitl dl'circuit imd maintaining the firstnaiiied 'electrcmzignet pein'ilnenfly ehei'gized when the second-maimed lect'iomilgnet' is connected in the ci'ifcliit, and p r.essu 1 e operated switch for opening and clcsingthe cont-relcircui-t.- -V

20. An antomixtie-contmll-ing aFpurates in accordancewvitli claim .1, -in \Yiich' the motor circuit switch is a speed regulating switch and in which the electromechanical means iinclu-deseontnol devices {or pespfic tix'ely shifting the switch between full speed and ent-out posit-ions fend. eadjusting the switch hetween ful l speed-and lbw-speed positions, and means 01" threwing eitheg 9f saild (OHlUOl devices inte and cuttof action; at wi'l; r

QIrAn automatic controlling-appamtus in flCCOl'dtlZ-ICC withjclaim 1,-in "w-hich vthe" 1 0w!- circuit switchis a speed regulating switch and in which -the"eiectromeehanieei means operates the vailve and"- switch fieradjusting the valve .lw'goym'ithe a'ction of the com pi-essen- 11 Ste a. predetermined pressure limit and then adjusting-the ,sWitcl-i to cut-cut position. I a. second electromechanical neahs for controllingthe wake and adjnstin-gthe swiitelhfor maintaining fl1e-;e0mpitess0r in action, after such predetermined p nessm eis reached, ntlei-"v spced;3a-nd means ior ten.- (lc'ringi the zip-p21 rati'is opeiia'tiwa by-ei-ther-of said electrmnechanicel'means et-{wil-l.

KAim Mii-IILER- 

